[RTTY] Decoding troubles after taking a break

[David G3YYD]

Actually 2Tone does not care what sampling rate that Windows default is set
at. It will always use 48K for decode and uses the Windows API to set it at
that for its sample rate. It decimates this internally to what is required -
in the case of 45.45 baud to a final rate of 1500/sec

Probably what happened is while you were not using the PC it did some power
down of various parts and in doing so probably did that to the sound card as
well. This is especially so if the sound card is USB connected. Many
motherboards use USB internally for the sound card connection.

When you returned and "activated" the PC powered up again it probably did
not power up the sound card correctly. I always operate my PCs with no power
down except for the monitors. But then if I am leaving the PC for a while I
switch off the AC supply to the monitors.

It is a good idea to run MMTTY at 12K sample rate as some (not all) sound
cards do not decimate their native speed accurately to 11025/sec but to the
nearest multiple of 300 which is 11100/sec. This will mean you will have a
slight frequency difference between 2Tone and MMTTY. MMTTY will be slightly
off the wanted mark/space tone.

73 David G3YYD

-----Original Message-----
From: RTTY [mailto:rtty-bounces at contesting.com] On Behalf Of Joe Subich,
W4TV
Sent: 16 July 2017 13:50
To: rtty at contesting.com
Subject: Re: [RTTY] Decoding troubles after taking a break


> I needed to take a break for dinner, so shut everything down for an 
> hour. When I came back and started everything up again, all 3 of the 
> decoders on my PC had trouble decoding anything. They would get some 
> decoded, then just stop decoding. Then they would start back to 
> decoding again. This happened on pretty much every QSO after the 
> break.
Is the "Default Format" of your sound card set correctly?

With 2Tone, you want the "Default Format" to be 48,000 Hz and you need to
define the Clock Rate in MMTTY (Config | Misc) to be 12000 Hz or you will
have sample rate issues.

73,

    ... Joe, W4TV


On 7/16/2017 9:31 AM, Mike Ricketts wrote:
> Perhaps someone here has some insight as to what was happening with my 
> decoding last night.
> 
> For the duration of the contest, I was running N1MM+ with MMTTY as the 
> engine, using an additional 2 decoding windows of 2Tone, and also had 
> the decoder going on my IC7300.
> 
> During the beginning (8 hours or so) of the contest everything was 
> working great.
> 
> I needed to take a break for dinner, so shut everything down for an hour.
> When I came back and started everything up again, all 3 of the 
> decoders on my PC had trouble decoding anything. They would get some 
> decoded, then just stop decoding. Then they would start back to 
> decoding again. This happened on pretty much every QSO after the break.
> 
> The decoder on the radio was doing fine, so I ended up using that for 
> most of the rest of the contest. So I know the signals were ok.
> 
> I thought maybe there was some errant process sucking up resources, 
> but I watched the performance monitor in task manager for a while, and 
> noticed nothing out of the ordinary. The only process with any 
> significant resource usage was MMTTY, and total CPU usage was 25% or 
> less, which is normal for me when running MMTTY. There were no scans, or
anything like that, running.
> 
> Thanks in advance for any ideas you may have on the cause.
> 
> 73,
> Mike ND9G
> _______________________________________________
> RTTY mailing list
> RTTY at contesting.com
> http://lists.contesting.com/mailman/listinfo/rtty
> 
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